Commercially available electrostatic copying machines of the type which perform processes wherein an electrostatic latent image formed on a photoconductor is developed by contacting the same with a dry developer material, and wherein the developed image is subsequently transferred from the photoconductor to a suitable supporting substratum such as paper, are generally provided with a dry developer material of the type which has a toner component including a thermally meltable resin mixed with a suitable toning pigment to facilitate thermally bonding the otherwise easily movable and smudgeable transferred image to the paper. Accordingly, such copying machines generally include a suitable heatable enclosure of fuser wherein the transferred-image bearing paper is typically heated to a temperature of from 100.degree. to 300.degree. C for image bonding purposes, before the paper is subsequently processed and/or discharged from the machine.
Inasmuch as such commercial machines are generally utilized by non-technical personnel, instruction manuals accompanying the same usually include indefinite instructions to the effect that the machine operator should "wait awhile" or a "few minutes" before utilizing the machine for copying purposes, to allow the fuser sufficient time to heat up to its bonding temperature level. On the other hand, a given copying machine may well be ready to be used after a delay of exactly 60 seconds after having been initially energized, under circumstances wherein the fuser space is initially at ambient temperature due to the machine not having been recently emergized; or in exactly 20 seconds, under circumstances wherein the fuser space is initially above ambient temperature due to the machine having been relatively recently used. Of course the aforesaid time intervals vary from machine to machine due to variations in toner materials, machine structure, service time intervals and other well-known factors. As a result, operators of copying machines must rely on their own experience with a particular machine in order to avoid wasting paper due to prematurely using the machine or wasting time due to waiting too long to use the machine. Accordingly;
An object of the present invention is to provide an improved electrostatic copying machine;
Another object is to provide an electrostatic copying machine, of the type which includes a heatable fuser space, with a circuit for controlling operation of the machine in consideration of the temperature of the fuser space; and
Yet another object is to provide such a control circuit with means for visually signaling the operator when the machine is ready to be used for copying purposes.